Add a test for [perl #17753].

p4raw-id: //depot/perl@19215

diff --git a/t/op/undef.t b/t/op/undef.t
index f6e36a5..1d16994 100755 (executable)
--- a/t/op/undef.t
+++ b/t/op/undef.t
@@ -5,7 +5,7 @@ BEGIN {
     @INC = '../lib';
 }
 
-print "1..27\n";
+print "1..28\n";
 
 print defined($a) ? "not ok 1\n" : "ok 1\n";
 
@@ -79,3 +79,9 @@ print $@ =~ /^Modification of a read/ ? "ok 23\n" : "not ok 23\n";
     @foo = ( a => 1 );
     print defined @foo ? "ok 27\n" : "not ok 27\n";
 }
+
+{
+    # [perl #17753] segfault when undef'ing unquoted string constant
+    eval 'undef tcp';
+    print $@ =~ /^Can't modify constant item/ ? "ok 28\n" : "not ok 28\n";
+}